Response of Leaf Morphological Traits to Environmental Factors of an Emergent Aquatic Plant Sparganium stoloniferum in Northwest Yunnan

To explore the leaf morphological adaptability of plateau wetland plant, this study selected typical plateau wetlands(Bita Lake, Napa Lake, Lugu Lake and Lashi Lake) in northwest Yunnan as the research sites. We determined the leaf morphological traits of their common emergent aquatic plant Sparganium stoloniferum, and collected their small environmental factors to explore the environmental adaptive strategies of S. stoloniferum and to detect the major environmental factors influencing the morphological traits of S. stoloniferum. The results showed that leaf size, stomatal density and size, vein density, leaf thickness, leaf mass per area and leaf dry mass showed significant differences among 4 study sites. Plants in higher altitude had smaller leaf size, lower stomatal density, larger stomatal size and lower leaf dry mass than those of in lower altitude; the leaf area, leaf width, stomatal density, stomatal index and leaf thickness decreased with the increase of latitude; the ratio of leaf length to width, stomatal size and specific leaf weight increased with the increase of latitude. Temperature was the major environmental factor affecting the morphological traits. Leaf size, stomatal density, leaf thickness and leaf dry mass were significantly positive correlated with annual mean temperature, annual mean temperature of the warmest month(WAT) and annual mean temperature of the coldest month, while stomatal sizes traits were significantly negative correlated with 3 temperature factors; vein density was also significantly positive correlated with WAT. Significant traits associations exist among the leaf morphological traits; leaf size traits were positively correlated with stomatal density, vein density, leaf thickness, leaf dry mass and leaf mass per area, while they were negatively correlated with stomatal size traits; leaf thickness was significantly positive with stomatal density and stomatal index, but it was significantly negative with stomatal size.